Adding route after PPTP connection is established

At a customer's office and their branch office we temporarily need a lan-to-lan VPN connection for the migration of their current network. At the head office we installed a Draytek, at the branch office we installed a WRT54G that's running on Satori firmware.

I set up the Draytek to connect to the WRT54G's built-in PPTP server. After the PPTP connection is established, a route needs to be added to provide the branch office's LAN access to the head office's LAN. I use the console to add the route, and all works well, until the PPP0 connection goes down, because then the route gets deleted.

I can't seem to figure out how to have the WRT add the route automatically when the PPP0 interface comes up. Adding the route add line to rc_firewall did not help. Does anyone have any ideas as to how this can be done?

Response related to the Linksys router
Are you setting a static router on the web interface "Advanced Routing" page? That should survive the reboot. I would recommend setting a static DHCP assignment for the Draytek unit on the "Administration" page under the sub heading "Dhcpd". Enter it like192.168.0.100 XX:XX:XX:XX:XX:XX name where XX:XX:XX:XX:XX:XX is the MAC of the Draytek unit (get it from the DHCP client list) and name is the name listed for the Draytek unit on that same list. This should give the unit the same IP every time it disconnects and ensure the static route is set.

No, I was not aware of that possibility. I used the console and typed the route add command. Your suggestion appears to work on my own WRT54G and I will try and see if it works on the customer's router next week. Thanks for your help.